This is an application for a K08 Mentored Clinical Scientist Research Career Development Award for Dr. Stephanie Mueller, a medical hospitalist and researcher at Brigham and Women's Hospital (BWH) in Boston, Massachusetts. The broad goal of the work in this application is to improve the safety and quality of care transitions of hospitalized patients. More specifically, the objectives of this proposal are to identify which patients benefit and do not benefit from transfer between acute care hospitals (inter-hospital transfer, IHT) as well as define the associated risks of IHT, and use this knowledge to develop an intervention to promote safer hospital transfers. This work will be carried out in three phases. First, CMS data will be used to determine the association of IHT with several outcomes, including cost, length of stay, and mortality among different populations of patients with common diagnoses. These analyses will employ advanced epidemiologic methods to control for confounding and examine interaction of patient and hospital characteristics with IHT on patient outcomes, including Cox regression analysis, propensity score analysis, and regression analyses with effect modification. The second phase will focus solely on transferred patients to allow for an in-depth analysis of transfer process factors and patient outcomes. In this phase, we will first employ qualitative methodology to conduct and analyze interviews of a cohort of transferred patients and caregivers, to gather a more detailed understanding of reasons for transfer, expectations of care, and satisfaction with the transfer process. Then, we will utilize local hospital data to quantitatively examine a cohort of transferred patients identifying specific of the transfer process (i.e., time of day of patient arrival) and patient characteristics that are associated with increased cost, length of stay and mortality. In the third phase of this work, we will use the information gained from the first two phases and existing knowledge about safe transfer practices to develop a standardized IHT process, and conduct a pilot study using interrupted time series methods to examine the impact of this intervention on the quality of patient transfer. This information will then be used to inform development of a multi-center, cluster randomized controlled trial as a future R01 submission. Throughout the award period, coursework, strong mentorship, input from a multi-disciplinary Advisory Committee, and institutional support will advance the candidate's methodological skills in epidemiologic analysis and hospital-based outcomes research. She will also further develop her ability to translate research findings into interventions that will successfully impact the clinical care of hospitalize patients. Taken together, this multi-faceted proposal will facilitate Dr. Mueller's development int an independent investigator in hospital- based quality improvement and patient safety research.